A statement late Friday by Sharif's soon-to-be ruling party describes Wednesday's strike as a violation of Pakistan's sovereignty and international law.

It does not mention the Pakistani Taliban's deputy leader, Waliur Rehman. After the strike, the Pakistani Taliban withdrew their offer of peace talks with Sharif's incoming government.

The statement says a Sharif aide conveyed his sentiments to the U.S. Embassy.

The U.S. regards such missile attacks as legal, but President Barack Obama recently described plans to further restrict drone use in the future. According to the statement, the aide described the strike as especially regrettable since it came within days of Obama's speech.